Numerical Analysis of Silicon Micromachined Gas Pendulum Tilt Sense Organ Temperature Field

An analysis of the sensitive mechanism of silicon micromachined gas pendulum tilt sense organ is made.Adopting the method of FEA (finite element analysis),the temperature field at two points heat source,when the two-dimensional enclosure was inclined,was obtained by application of the program ANSYS-FLOTRAN CFD and a series of procedures,such as modeling,meshing,loading and equation solving.The numerical results show that in the level state,the temperatures at two points heat source are two points in the same isotherm;however,the temperatures are not the same when the enclosure is inclined.The difference of the temperatures will increase with the augment of the tilt angle,and contrarily it will decrease.That is the characteristic used to sense the transformation of obliquity.

A hydrogen-bonded organic framework containing fluorescent carbazole and responsive pyridyl units for sensing organic acids

Hydrogen-bonded organic frameworks(HOFs)are a promising candidate for optical sensing,but the lack of effective design strategies poses significant challenges to the construction of HOFs for organic acid sensing.In this work,the first HOF for organic acid sensing is reported by constructing a multiplepyridine carbazole-based dense HOF,namely HOF-FJU-206,from a tripyridine-carbazole molecular 3,6-bis(pyridin-4-yl)-9-(4-(pyridin-4-yl)phenyl)-9H-carbazole(CPPY)with carbazole center for luminescence,pyridyl sites for its responsive of hydrogen proton,and narrow channels in the dense framework for the diffusion of hydrogen protons.HOF-FJU-206 exhibits differential responsively fluorescence sensing and recovery properties to formic,acetic,and propionic acids with different molecular sizes and p Kavalue(acid dissociation constant).The dissociation degree of various acids can be determined by analyzing the slope of changes in both peak wavelength and intensity of in-situ fluorescence,which easily enables the dual-corrective recognition of different acids.The varying degree of protonation at pyridine sites is proved to be the reason for differential sensing of various acids,as demonstrated by1H NMR spectra,X-ray photoelectron spectroscopy(XPS)characterization,and modeling studies.

Smart Microcavity on the Tip of Multi-Core Optical Fiber for Gas Sensing

We designed and fabricated a smart microcavity sensor with a vertically coupled structure on the end face of a multi-core fiber using two-photon lithography technology. The influence of gap in vertical coupling structure on the resonance characteristics of bonding and anti-bonding modes in the transmission spectrum was studied through simulation and experiments. The results indicate that the bonding and anti-bonding modes generated by the vertical coupling of the two microcavities, as well as the changes in the radius and refractive index of the micro-toroid, and the distance between the microcavities caused by the absorption of vapor during the gas sensing process, exhibit different wavelength shifts for the two resonant modes. Smart microcavity sensors exhibit sensitivity and sensing characteristics. .

Micro-interfaces modulation by UV-ozone substrate treatment for MPEA vapor fluorescence detection

Drug abuse directly endangers human health and social security,hence its sensitive and rapid detection is vitally important.In recent years,organic film-based fluorescent sensing technology has attracted more and more attention in the detection of drugs and explosives due to its advantages of simple operation and rapid detection.For film-based fluorescent sensors,in addition to sensitive materials,the surface morphology of the film is also an important factor affecting the performance.In previous studies,the regulation of surface morphology mainly depends on concentration changes or complex templates.Here,a novel fluorescent polymer probe was designed and synthesized,and a simple and efficient ultraviolet(UV)-ozone substrate treatment method is used to adjust their surface morphology.The results show that film has an excellent fluorescence enhancement effect upon exposure to methylphenethylamine(MPEA,a simulant of methamphetamine)vapor.The sensing effect of the film is significantly improved after UV-ozone substrate treatment,and the limit of detection was decreased by 10.4 times from 2.59 to 0.25 ppm.Further experiments show that the sensing performance of other fluorescent probe can also be improved by the UV-ozone substrate treatment.This convenient and general method may become a very effective approach to improve the performance of film-based fluorescent sensors.